Unchanged PM2.5 levels over Europe during COVID-19 were buffered by ammonia

The coronavirus outbreak in 2020 had devastating impact on human life, albeit a positive effect for the environment reducing emissions of primary aerosols and trace gases and improving air quality. In this paper, we present inverse modelling estimates of ammonia emissions during the European lockdowns of 2020 based on satellite observations. Ammonia has a strong seasonal cycle and mainly originates from agriculture. We further show how changes in ammonia levels over Europe, in conjunction with decreases in traffic-related atmospheric constituents modulated PM2.5. The key result of this study is a -9.8% decrease in emissions in the first half of 2020 compared to the same period in 2016–2019 attributed to restrictions related to the global pandemic. We further calculate the delay in the evolution of the emissions in 2020 before, during and after lockdowns, by a sophisticated comparison of the evolution of ammonia emissions during the same time periods for the reference years (2016–2019). ..., - FLEXPART v10.4 sensitivities for 6 model levels using chemistry loss after taking into account changes in emissions of NOx and SO2 in the calculations (see also associated paper): AVE_FOOTPRINT_L1_chem.nc, AVE_FOOTPRINT_L2_chem.nc, AVE_FOOTPRINT_L3_chem.nc, AVE_FOOTPRINT_L4_chem.nc, AVE_FOOTPRINT_L5_chem.nc, AVE_FOOTPRINT_L6_chem.nc
- FLEXPART v10.4 sensitivities for 6 model levels using chemistry loss after taking into account changes in emissions of NOx and SO2 in the calculations (see also associated paper): AVE_FOOTPRINT_L1_nochem.nc, AVE_FOOTPRINT_L2_nochem.nc, AVE_FOOTPRINT_L3_nochem.nc, AVE_FOOTPRINT_L4_nochem.nc, AVE_FOOTPRINT_L5_nochem.nc, AVE_FOOTPRINT_L6_nochem.nc
- Different surrounding estimates of posterior emissions covering 2°, 3° and 4° from each grid-cell: 2deg.tar.gz, 3deg.tar.gz, 4deg.tar.gz
- Performance calculations for the prior and posterior emissions against the dependent observations (CrIS): Correction_R4.tar.gz
- Forward simulations with FLEXPART v10.4 using..., , # Unchanged PM2.5 levels over Europe during COVID-19 were buffered by ammonia

[https://doi.org/10.5061/dryad.12jm63z1q](https://doi.org/10.5061/dryad.12jm63z1q)

## Description of the data and file structure

1\. Title of Dataset: Unchanged PM2.5 levels over Europe during COVID-19 were buffered by ammonia

2\. Author Information

Corresponding Investigator

Name: Dr Nikolaos Evangeliou

Institution: NILU - Norwegian Institute for Air Research, 2007 Kjeller, Norway

Email: [[e-mail]](mailto:[e-mail])

Co-investigator 1

Name: Dr Ondřej Tichý

Institution: The Czech Academy of Sciences, Institute of Information Theory and Automation, Prague, Czech Republic

Co-investigator 2

Name: Ms. Marit Svendby Otervik

Institution: NILU - Norwegian Institute for Air Research, 2007 Kjeller, Norway

Co-investigator 3

Name: Dr Sabine Eckhardt

Institution: NILU - Norwegian Institute for Air Research, 2007 Kjeller, Norway

Co-investigator 4

Name: Dr. Yves Balkanski

Institution: Laboratoire des ...